Page 4

Cells
Diffusion
- Movement of molecules from a higher to a lower concentration until equilibrium is reached
- Gases move through plasma membranes by diffusion
- Factors affecting rate:
- Distance: e.g. membranes in lung are very thin
- Concentration gradients: the steeper the gradient, the faster the diffusion rate…

Page 5

Cells
- When answering a question about osmosis, state:
a) Where the highest water potential is
b) Direction of movement
Experiment Descript ion
c) Through partially permeable membrane
d) Resulting in increase/decrease of mass Water enters visking
tubing (proven by
increase in mass)